真正的四轮驱动车辆外文文献翻译、中英文翻译

资料来源： True Four Wheel Drive System For Vehicle Four Wheel Drive System For Vehicle真正的四轮驱动车辆ABSTRACTA drive train for a four wheel drive vehicle including a front difforential engaged with a front drive shaft and front axles through a front differential gear set. The front differential includes a front bi-directional overrunning clutch that controls transmission of torque transfer between the front drive shaft and the front axles. A rear differential is engaged with rear axles and the transmission through a rear differential gear set. The rear differential includes a rear bi-directional overrunning clutch that controls torque transfer between the transmission and the rear axles. The differentials are configured with a gear ratio that is within five percent of a l: 1 gear ratio.TRUE FOUR WHEEL DRIVE SYSTEM FOR VEHICLERELATED APPLICATIONThis application is related to and claims priority from U.S. Provisional Application 61/677,820, the disclosure of which is incorporated herein by reference in its entirety.FIELD OF THE INVENTIONThe invention relates to drive systems and, more particularly, to an improved drive system designed to provide substantially true four wheel drive capability.BACKGROUNDprovide four wheel drive capability. Those systems are all designed to engage all four wheels but also allow a speed differential across the axle. However, many of those systems do not provide true four wheel drive where each wheel provides substantially the same speed during all drive conditions. Instead, the systems permit some degree of slippage. Current Four Wheel Drive Bi-Directional Overrunning Clutch Systems I illustrates the drive system for a conventional four wheel drive vehicle with a front bi-directional overrul111ing clutch. The drive system includes four wheels. The rear left wheel RLW is connected to a rear differential RD through a rear left axle RLA. The right rear wheel RRW is com1ected to the rear differential RD through a rear right axle RRA. The front left wheel FLW is col111ected to a front differential FD through a front left axle FLA. The front right wheel FRW is connected to the front differential FD through a front right axle FRA.mission T through a rear drive shaft RDS. The front differential FD is connected to the transmission T through a front drive shaft EDS. Straight Line Operation: During straight line driving while the vehicle is in a four wheel on demand mode (i.e., four wheel drive engages only when needed) both rear wheels RLW, RRW are the primary drive wheels and are co1111ected through the rear differential RD to rotate at the same speed. In a non-slip condition of the rear wheels, the front drive shaft FDS is engaged to the front differential FD, but the front axles FLA, FRA are not engaged with the front differential. That is, the front axles FLA, FRA and front wheels FLW, FRW are generally in an overrun condition such that the front differential FD is not driving the front axles FLA, FRA and, therefore, not transmitting any torque to the front wheels. This means that the front wheels FLW. FRW are free to rotate at their actual ground speeds. In order for the front wheels to be engaged, the rear wheels must slip (break traction) or spin increase speed approximately 20% faster than the front wheels. While driving in a straight line, once the rear wheels slip 20%, the overrunning condition in the front differential ED is overcome and both front axles are engaged. This results in the transmission T transmitting torque to the front wheels thru the front drive which is geared in a way that decreases the vehicles ground speed. When the ground speed has increased so as to cause the rear wheel speed to be rotating less than 20% faster than the ground speed, or the speed of the rear wheel has decreased so as to be rotating less than 20% faster than the ground speed, the front wheels will start to overrun again and no torque will be transmitted to the front wheels. Turning Operation: In a comer all four wheels are trying to rotate at different speeds, This is shown on the chart in FIG. 4 which depicts wheel revolutions vs. turning radius for all four wheels. For a vehicle with alocked rear axle or solid axle (i.e., an axle where the rear axles RLA, RRA are connected, either physically or through gearing, such that they always rotate at the same speed) the ground speed is dictated by the rear outside wheel due to vehicle dynamics (i.e., the rear outside wheel has to cover more circumferential distance than the rear inside wheel when turning around a common axis.) Since both rear wheels are rotating at the same speed and the rear outside wheel is the drive wheel the rear inside wheel is beginuing to scrub or drag on the ground. This can cause inefficiencies, turf wear and/or tire wear. The primary reason conventional bi-directional ovemnming clutch four wheel drive systems have a 20% under drive is for turning. With the rear outside wheel dictating ground speed the front inside wheel will go slower than the rear outside wheel as shown in FIG. 4. If there is no under drive the bi-directional oveITllllling clutch for the front inside axle would engage and begin to drive torque. This would cause the front inside wheel to travel at an incorrect speed and would create inefficiencies, turf wear, tire wear and, more importantly, torque steer. As mentioned above, during a tum the rear outside wheel is dictating ground speed, the rear inside wheel is scrubbing or dragging, and the front wheels are overrunning. Referring to FIG. 5 which depicts the percentage difference between the front and rear wheel speeds versus the turning radius of a locked rear axle, once the rear outside wheel slips or spins a certain percentage, dictated by vehicle geometry and turning radius. the bi-directional overru1ming clutch controlling the transfer of torque to the front inside wheel will engage and drive torque through the front inside wheel At this time both rear wheels and the front inside wheel are driving torque and their speed is dictated by the drive line, not ground speed. The front outside wheel is still ovemmning allowing it to spin at the rotational speed dictated by ground speed and vehicle geometry. When both rear wheels and the front inside wheel slip a certain percentage, again dictated by vehicle geometry and the turning radius, the bidirectional clutch controlling torque transfer to the front outside wheel will engage and torque will be transmitted to all four wheels, even though three of the wheels would be slipping. Wedging The existing drive system is prone to a condition called wedging. Wedging occurs when torque is being driven through the bidirectional over-numing clutch and a rapid direction change occurs. This can cause the rollers in the clutch to be positioned or locked on the wrong side of the clutch profile preventing the output hubs from overru1ming. The effect causes the front drive to act like a solid axle, but with the 20% speed difference in the drive line it results in scrubbing of the front tires. This condition can cause excessive tire wear and turf wear. This also effects steering effort and stability of the vehicle. The vehicle will try to maintain a straight line due to the effect of the front drive acting like a solid axle.Because of the wedging condition in the current systems precautions are put into place to help reduce wedging. One of these precautions is the use of a cut-off switch so that when the vehicle is shifted from the forward direction to the reverse direction so as to automatically disengage the bi-directional overrum1ing clutch (for example, shutting off the coil that is indexing the roll cage). This system also uses the cut-off switch when transitioning from the reverse direction to the forward direction. Another way to reduce wedging is the use of a switch, when the brakes are applied, that will interrupt power to the 4 wheel drive system. Many other methods can be used to reduce wedging, but none are 100% percent effective with the 20% difference in drive line speeds. Conventional Drive Systems:A common conventional drive system would have the same vehicle layout as in FIG. 1, but the mechanisms in the front and rear differentials would be different. Most common drive systems have an open differential with the ability to be locked into a solid axle in both the front and rear differentials. The drive line in a conventional system would also be using a drive line that is geared to a 1: 1 ratioStraight Line Operation: During straight line driving while the vehicle is in four wheel drive and all the axles are unlocked, all four wheels are rotating at the same speed. This is due to the drive line being geared at 1:1 ratio and the front and rear differentials are being driven at the same speed and no differentiation is needed across the axles. This is also the case when any or both of the front and rear differentials are in a locked position creating a solid axle. Turning operation:Conventional four wheel drive systems will normally have the rear differential locked and the front drive will be in the open state until the solid axle mode is selected by the user. During turning with a solid axle in the rear differential and an open differential in the front, only one tire is turning at the correct ground speed. Due to vehicle dynamics the rear outside wheel is considered the drive wheel and is turning at ground speed. The inside rear wheel is being driven at the same speed as the rear outside, but the ground speed is slower. This causes the inside rear wheel to scrub or slip during a tum. (0023 Since the two front wheels are connected to an open differential, they are allowed to differentiate across the axle, However, the differential is being driven at an incorrect speed. That is, the front open differential takes the input speed and averages it across the axle. In a normal non slip condition the average speed across the axle is centered about the middle of he vehicle. Since the rear outside wheel is traveling at a different speed ( or arc) than the average of the two front wheels, both front wheels are scrubbing when in a tum causing un-needed drive line torque or drive line bind. Once the operator selects the solid axle mode of the vehicle, both front wheels are locked together and they now rotate at the same speed. When turning, the outside front wheel is going slower than what ground speed dictates, thus causing the wheel to scrub. At the same time the inside front wheel is going faster than the ground speed dictates causing it to, likewise, scrub. Due to the wheels being driven at the wrong speeds in a comer, conventional drive systems are not very efficient. They cause severe turf damage or wear due to the tires scrubbing. They also cause tire wear due to the scrubbing. The tires being driven at the wrong speeds also cause issues with steering and turning performance of the vehicle. The difference between ground and actual wheel speed results in the wheels trying to straighten the vehicle out. This causes increased wear in steering components, as well as rider fatigue since increased input is needed to maintain the vehicle in the tum. Many manufacturers have added power steering to try to minimize operator input when cornering because of the four wheel drive operations. A need therefore exists for an improved four wheel drive system that incorporates bi-directional overrunning clutches in a drive system that minimizes scrubbing in all wheels while permitting 1.1 or near 1: 1 gear ratio between the front and rear axles. SUMMARY OF THE INVENTIONThe present invention is directed to drive train for a four wheel drive vehicle. The drive train includes a front drive shaft connected to a transmission. Two front axles with each axle connected to a corresponding front wheel. A front differential is engaged with the front drive shaft and the front axles through a front differential gear set. The front differential includes a front bi-directional overrunning clutch that controls transmission of torque transfer between the front drive shaft and the front axles. The front bi-directional ovemmning clutch includes a front clutch housing connected to the front drive shaft so as to be rotatable by the front drive shaft, the front clutch housing including an inner cam surface. A front roller assembly is located inside the front clutch housing and adjacent to the cam surface. The front roller assembly includes a roll cage with a plurality of rollers arranged in two sets within slots formed in the roll cage, the rollers are rotatable inside the slots. A plurality of springs are arranged in the roll cage to position the rollers within the slots. The roll cage is rotatable within the front clutch housing. (0029 Two front hub are located in the front clutch housing. Each hub is positioned radially inward from a set of the rollers located between an outer surface of the front hub and the im1er cam surface. Each front hub is engaged with an axial end of one of the front axles so as to rotate in combination with the axle. The front hubs are independently rotatable within the roll cage and the front clutch housing. A front engagement control assembly is located within the housing and controls engagement and disengagement of the front bi-directional overrunning clutch. The front engagement control assembly includes an electromechanical device that is controllable for impeding rotation of the roll cage relative to the front clutch housing so as to index the roll cage relative to the front clutch housing. When the engagement control assembly is activated and the roll cage is indexed relative to the clutch housing, the front bi-directional overrunning clutch is configured to transmit torque from the front drive shaft to the front axles when the front clutch housing is rotating faster than the front axles. Also, when the vehicle is traveling straight the front differential is configured to begin to transmit torque from the front drive shaft to the front axles at a first speed. The gear train including two rear axles, each axle com1ected to a corresponding rear wheel. A rear differential is engaged with the rear axles and the transmission through a rear differential gear set. The rear differential including a rear differential housing and a rear bi-directional overrunning clutch that controls torque transfer between the transmission and the rear axles. The rear bi-directional overrunning clutch includes a rear clutch housing located within the rear differential !musing and rotatable by the transmission, the rear clutch housing including an inner cam surface. A rear roller assembly is located inside the rear clutch housing and adjacent to the cam surface. The rear roller assembly includes a roll cage with a plurality of rollers arranged in two sets within slots formed in the roll cage. The rollers are rotatable inside the slots. A plurality of springs are arranged so as to position the rollers within the slots. The roll cage is rotatable within the rear clutch housing. Two rear hubs are located in the rear clutch housing. Each hub is positioned radially inward from a set of the rollers located between an outer surface of the rear hub and the im1er cam surface. Each rear hub is engaged with an axial end of one of the rear axles so as to rotate in combination with the axle. The rear hubs are independently rotatable within the roll cage and the rear clutch housing.The rollers in each set of the rear roller assembly are adapted to wedgingly engage the corresponding rear hub to the rear clutch housing when one of either the rear hub or rear clutch housing is rotating faster than the other so as to transmit torque from whichever is faster to whichever is slower. The differentials are configured such that when the vehicle is traveling straight and the rear differential is transmitting torque to the rear axles. The rear differential is configured to rotate the rear axles at a second speed, and where the difference between the first speed and the second speed is five percent or less. In one preferred embodiment, the difference between the first speed and the second speed is less than about three percent. In another embodiment there is substantially no difference between the first speed and the second speed.In one embodiment, the front bi-directional overrunning clutch includes an armature plate that is engaged or connected with the front roll cage such that the armature plate rotates with the roll cage. The front engagement control assembly impedes rotation of the roll cage relative to the front clutch housing by engaging the amiature plate so as to index the roll cage relative to the clutch housing.Preferably the hubs are substantially coaxially aligned with each other within the housing. and are adapted to rotate about a common axis within the housing. In one embodiment, the rear differential is part of a transaxle which is engaged with the transmission. 。 In another embodiment the front differential is part of a transaxle which is engaged with the transmission. The foregoing and other features of the invention and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments, as illustrated in the accompanying figures. As will be realized, the invention is capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive.摘要一种用于四轮驱动车辆的传动系统，包括与前驱动轴接合的前差速器和通过前差速齿轮组的前轴。 前差速器包括前双向超越离合器，其控制前驱动轴和前轴之间的扭矩传递的传递。 后差速器通过后差速齿轮组与后轴和变速器接合。 后差速器包括控制变速器和后轴之间的扭矩传递的后双向超越离合器。差速器构造成具有百分之五内1：1的齿轮比误差比。真正的四轮驱动系统车辆相关申请本申请与美国临时申请61 / 677,820相关并要求其优先权，其公开内容通过引用整体并入本文。本发明涉及驱动系统，更具